docs: def add_gene_ids(self, genes_list):
          """Add gene IDs manually into the GEM-PRO project.
  
          Args:
              genes_list (list): List of gene IDs as strings.
  
          """
          orig_num_genes = len(self.genes)
  
          for g in list(set(genes_list)):
              if not self.genes.has_id(g):
                  new_gene = GenePro(id=g, pdb_file_type=self.pdb_file_type, root_dir=self.genes_dir)
                  if self.model:
                      self.model.genes.append(new_gene)
                  else:
                      self.genes.append(new_gene)
  
          log.info('Added {} genes to GEM-PRO project'.format(len(self.genes)-orig_num_genes))